Helicopter with jet-driven lift



Dec. 25, 1951 c. ca. PULLIN HELICOPTER WITH-JET-DRIVEN LIFTI'ROTOR 6 Sheets-Sheet 1 Original Filed April 22, 1945 INVENTOR (YR/1. G. PULL/N A TTOENE'YS Dec. 25, 1951 c. G. PULLIN 23,443

HELICOPTER WITH JET-DRIVEN LIFT ROTOR Original Filed April 22, 1943 6 Sheets-Sheet 2 TTORNEKS C. G. PULLIN HELICOPTER WITH JET-DRIVEN LIFT ROTOR Dec. 25, 1951 6 Sheeis-Sheet 5 Original Filed April 22, 1943 IMVENTOK mu. PuL/N 0/7 ATTORNEYS Dec. 25, 1951 c. s. PULLIN 23,443 HELICOPTER WITH JET-DRIVEN LIFT ROTOR Original Filed April 22, 1943 s Sheets-Sheet 4 INVENTOR RM 6}. PM N I ATTORNEYS Dec. 25, 1951 c. G. PULLIN 23,443

HELICOPTER WITH JET-DRIVEN LIFT ROTOR Original Filed April 22, 1943 V 6 Sheets-Sheet 5 C. G. PU LLlN HELICOPTER WITH JET-DRIVEN LIFT ROTOR Dec. 25, 1951 6 Sheets$heet 6 Original Filed April 22, 1943 INVENTOR YRI'L Q PULL/N V ATTORN F Reissued Dec. 25, 1951 Re. UNITED STATES PATENT OFFICE HELICDPTER WITH J ET-DRIVEN LIFT ROTOR Cyril George Pullin, Moseley, Birmingham, England, assignor, by mesne assignments, to Autogiro Company of America, Philadelphia, Pa., a corporation of Delaware Original No. 2,429,646, dated October 28, 1947. Serial No. 484,063, April 22, 1943. Application for reissue October 9, 1951, Serial No. 250,407. In Great Britain April 22, 1942 43 Claims. (Cl. 170135.4) Matter enclosed in heavy brackets I: appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue This invention relates to helicopters with jetdriven lift rotors.

An object of the invention is a closer approach to a solution of the problems of stability and controllability, especially at low translational speeds, as when hovering and rising from the ground.

My researches indicate that this problem is closely connected with that of eliminating torque reaction between the aircraft and its rotor (or rotors) and that if the rotor is torque-locked to be capable of varying their coning angle, the constraint referred to under heading above ensuring that all the blades vary their coning angle equally.

Preferably the centre of the spherical or universal joint referred to under heading (a) above, is arranged to coincide with the vertex of the cone in which the blade axes lie when the blades are at their normal coning angle, which depends only on the R. P. M. of the rotor and its thrust.

to the rest of the aircraft, 1. e. that there is torque m It will be seen that the connection of the reaction between them, the stability characterblades to the swash plate not only causes a istics of the rotor cannot be separated from those cy ca Variation of blade pitch a e W t of the rest of the aircraft, but the aircraft-rotor axes of the blade tip path and of the swash plate assembly must be treated as awhole. This indiverge but also causes an equal decrease or introduces so many factors into the problem that crease of pitch angle Of all the blades When the its solution is a matter of great difliculty. coning angle increases or decreases respectively.

Broadly the present invention consists in com- The ro o b a are P ed w j reacbining with a lifting rotor having inherently tion nozzles, P a y near a their p stable characteristics (in free rotation, i. e. rorected rearwardly (with reference to the directation without torque reaction), means for drivt o of rotation), which nozzles are fed With a ing the rotor by jet reaction applied to the blades working fluid from a generator" Ca ed in he themselves, thus entirely eliminating torque reraft body, t e f u d being led u S action between the rotor and body. ably disposed passages within the hub assembly More particularly the rotor comprises the 01- and the blades themselves and the articular and lowing features, conducive to inherent stability: O V j s of the ub ass b y and 0f t e (a) The non-rotative member of the rotor hub 53?: i t fifi z f s ggi z g;

assembly is mounted on the aircraft body suitable device for providing a stream of working 2:; g g' g zgi 32 3 2 353: fluid of appropriate mass flow and imparting to plane, th1s stream the required energy.

The blade mounting articulations as well as (b) The blades are mounted on the said rotative providing for twisting (pitch change) and conmember was to be free to turn about their ing of the blades may also allow lead/lag disradial axes and vary the blade pitch. placements of individual blades, if desired.

3 A helicopter of the preferred form hereinbegf figzf fg gfiii also comprises fore described will have the following functional characteristics: (0) The rotor blades are so constrained (with reference to the mtative hub member) that (1) There will be not torque reaction between the path swept by the blade tips is always 40 the rotor and body; coaxial with the rotative member of the (11) The angular velocity of the rotor will be hub assembly. steady, 1. e. there W111 be no periodic fluctuations, owing to the absence of (d) The blades are connected to a swash plate or Hookes joint eff t because, whatever equivalent mechanism such that a change t 1 t attitude of blade tip path of attitude of the blade tip path relatively to and aircraft, body, the blades do not the swash plate causes a cyclical variation flap relativdy to t rotative member of blade pitch tending to restore coaxiality of the hub assembly; parallelism of the axes of the blade tip (iii) For the same reason no centrifugal couples path and the swash plateare imposed on the rotor hub and its Flying control is obtained by connecting the swash plate to the pilot's controls, so that control movements vary the attitude of the swash plate in any azimuth.

In addition the blades may be so mounted as mounting;

(iv) The rotor is not directly constrained with respect to the aircraft body, the only constraint being an indirect one, exercised by the swash plate, operating by compensating owing to the induced change of cyclic pitch variation;

(vi) Axial gusts are self-cempen'sating' owing to the change of mean pitch angle caused by change of conin'g angle:

(vii) The R. P. M. are self-governing, for the same reason as in heading (vi) above;

(viii) No couples are transmitted from the rotor to the aircraft body, but only simple forces, viz. thrust along the axis or the blade tip path and in translational flight a small down wind force; there may also be a small "cross wind force. 7 The last two forces are merely equivalent *to a slight displacement of the thrust axis from coincidence with the axis of the bladetip path and do not affect the g pendular stability of the aircraft;

(ix) The flying controls are substantially irreversible and embody what is effect a servo-action.

Another feature of the invention consists in utilizing the jet reaction nozzle devices for mass balancing the rotor blades, by placing them so that the of the blade is brought far enough forward, i. e. toward the leading edge, to ensure that the resultant of inertia, centrifugal and aerodynamic forces acting on the blade does not cause excessive twisting of the blade and constitutes with the elastic restoring forces of the blade a stable system which will not give rise to flutter.

A further feature of the invention consists in "providing adjustable connections between the swash plate and the blades, such that the gear ratio between angular displacement of the swash plate relatively to "the blade tip path and amplitude or cyclic pitch variation ma y be varied within w ide limits. Alteration-of the adustm'eat will "also vary the gear-ratio between change of cor-ring angle and change of mean "blade pitch.

If desired the swash plate d'a tum may be bodily movable in the (mean) axial direction, being provided with a suitable additional control tor this purpose, whereby the mean pitch angle ot "the rotor blades may be varied.

The jet reaction nozzles are preferably placed 'a t' or e1ose to the rotor blade tips inorler t'o obtain the-best ratio 'between'the discharge velocity v and the circumferential velocity of the nozzles.

one preferred arrangement the nozzle orifices are so disposed as to be flush with the trail ing edge of the blade aerofoil section. In an alternative preferredarrangement the jet orifices i are situated on the upper side of the blades at or close to theposition of maximum blade thickness. It is considered that the latter-arrangement may be advantageous because both the driving and aerodynamic forces willb-e applied close to the elastic and mass axes of the blade A and because the external airstream into which ill Fig 2 is a vertical half-sectional view of the central part of the rotor and its mounting structure;

Fig. 3 is a partial plan view, partly sectioned,

of the rotor hub and the root of one blade;

Fig. 4 is a view in side elevation of the rotor hub and its mounting structure showing also somew at diagrammatically the arrangement of the 'flying' controls;

Fig. 5 is an isometric view, partly sectioned, of the rotor hub and its mounting structure;

Fig. 6 is a sectional plan view of the root of one rotor blade;

Fig. 7 is a plan view of the outboard part of one rotor blade;

Fig. 8 is a view of the same in elevation taken from the trailing edge:

' Fig. '9- is a sectional plan View of the same;

Fig. 10 is a plan view of the tip of an alternative form of rotor blade; and

Fig. 11 is a view of the same in section along the line X-X. H

Referring to Fig. '1, the airframe of the helicopter comprises a body 2], undercarriage '22, tail wheel 23, tailplane '24, fin 25 and rudder 2E. Secured to the top of the body is a rotor-supporting structure comprising legs 27 and rotor mounting member 28 on which is mounted the rotor comprising a hub 2 and radial bladestfl.

In the front part of the body is situated a plant generally indicated at 3! for producing a stream of energised gaseous fluid, which may be air compressed and heated with or without the admixture of products of combustion, for driving the rotor by .jet reaction. The whole of this plant will hereinafter be referred to for brevity as the generator. The fluid eilluent from this generator is conducted by means of a trunk 32 to the interior of the hollow rotor mounting 11161.nber 28.

The pilot of the helicopter is indicated in dotted lines at 33, and the flying controls comprise a rocking column 34, supported on the rear pylon leg 21 byauniversal joint 35, and a pitch control lever 36 connected by rods 31 and Stand bell crank levers 39, 40, with an upright rod 4!. the rods being indicated by dotted lines. The further connections of the control column 34 'andpitch control rod Al to the mechanism controlling the rotor "are illustrated in Fig. 4 and will be further described with reference thereto.

Referring. to Figs. 2 to 5, the hollow rotor "mounting member 28 is secured at its lower end by bolts 12 t'o a collar -43 and also to a flange 44 on the upper end of the trunk 32, the .joint thus formed being sealedby gaskets 45, 46 The collar 43 is secured by appropriate means (not shown) to the legs 2 of the rotor mounting structure. The "mounting member 28 terminates at its upper end in a hollow spherical extension 41 onwhic h -is supported a tiltable member consisting of an upper half 48 and a lower half 49 secured together by studs 50, the joint between the two halves being rabbeted and sealed by a :gasket St. The interior of the tiltable member 48, i9 is recessed to take packing rings 52, 53 made-of moulded compressed carbon formed with female spherical :faces adapted to ride on the male spherical faces of the upper and lower parts of the spherical extension 4'! of the hub mounting member, the contact surfaces between the carcan rings 52, 53 and the extension 41 b'eing "parts of the sam'esphere. The purpose of these carbon rings 52, 53 is not only to provide an ahfi fl'ictlon bearing between the 'm'du'rlting member extension 41 and the tiltable member 48, 49, but to provide a gas-tight joint between these members, and to ensure this the carbon rings may be lapped onto the faces of the extension 41 with which they cooperate and an interferencefit is allowed for in the lapping and subsequently obtained in tightening up the studs 50. The spherical joint between the mounting member extension 41 and the tiltable member 48, 49 thus enables the latter to tilt upon the extension 41 in any vertical plane. In this context, and in what follows, the vertical is considered to coincide with the centre line CL indicated in chain dotted lines of the rotor mounting member 28. This line is in fact substantially vertical when the helicopter is in its normal fiying attitude.

To prevent the tiltable member 48, 49 from rotating upon the mounting member 28, 41 about the axis of rotation of the rotor, which in its mean position coincides with the vertical centre line CL, a cap member 54 which completes the top of the upper half 48 of the tiltable member. being secured thereto by studs 55, is provided with a splined boss 58 carrying a splined shaft 51 connected by means of a universal joint, generally indicated at 58, with a plug 59 secured in a central recess of a trumpetshaped part 69 secured to the upper part of the spherical extension 41 of the rotor mounting member 28. This trumpet-shaped part serves partially to stiffen the spherical extension 41 and partly as a guide for the working fluid which flows from the trunk 32 through the tubular lower part 28 of the rotor mounting member into the hollow spherical extension 41 of the same member, the lower part of which is also provided with an annular fairing GI which, together with the trumpet-shaped part 80, forms a duct or passage for the workin fluid of streamlined form and without abrupt change of crosssection whereby a smooth and progressive transition from axial to radial flow of the fluid is obtained. This passage terminates in an annular orifice 62 which extends all round the spherical extension 41 except where it is interrupted by narrow elements 63 of the extension 41 which are left to provide an integral connection between the top and bottom halves of the extension 41 (see Fig. Corresponding with the annular orifice 82 of the spherical extension 41 is an interrupted annular orifice 64 provided in the top half 48 of the tiltable member which continues the passage for the working fluid in a radial direction.

Externally of the tiltable member 48, 49 is mounted a rotative rotor hub 85. This rotates on bail thrust bearings 66, 81, supported respectively in the lower half 49 of the tiltable member and in the cap member 54 completing its upper half 48. The outer race of the bearing 61 is carried in an extension 68 secured by studs 59 to the hub 85 and this race is locked by a threaded cover 18 enclosing the top of the hub. Gas sealing of the clearance between the hub 65 and the lower half 49 of the tiltable member is provided by a number of spring rings 1| mounted in'grooves of a flanged ring 12 secured to the part 49, the rings 1I bearing against an internal cylindrical face of a flanged rin 13 carried by the hub.

The hub 65 is provided with three integral extensions 14 constituting blade root housings in which are articulated blade mounting stubs 15.

In orderthat the blades may be free to vary their coning angle and to have some freedom to lead and lag from their mean radial positions, the inboard ends of the stubs 15 are formed with male spherical faces 15 which are engaged by corresponding female spherical faces of blade housing nuts 11 which screw into the blade housin 14. The inner, spherical face of the blade housing nut 11 is provided with annular grooves into which are moulded inserts 11a of graphite-impregnated material constituting a self-lubricating gas seal between the blade housing nut 11 and the spherical faces 16 on the inboard ends of the blade mounting stubs 15. Damping of lead/lag and coning movements of the blades is provided by rings 18 of friction material which are pressed against internal spherical faces of the blade mounting stubs 15 by springs 19 mounted in recesses of members 88 carrying the friction ring 18 and slidable on spigots 8| secured to the hub 65.

Rotatable on the blade mounting stubs 15 are blade roots 82 being mounted by means of two ball thrust bearings, of which the outboard, 83, carries the centrifugal loading of the blade and the inboard, 84, is a pre-loading bearing, the pre-load being applied by means of a pro-load nut 85 locked by a lock nut 85 and tab washer 81.

Gas sealing of the clearance between the blade root 82 and blade mounting stub 15 is obtained by three spring rings 88 mounted in grooves at the outboard end of the blade mounting stub 15 and bearing on an internal cylindrical surface of an extension member 89 secured to the blade root 82. It will be noted that in both the ring seals 88, 8 9 and II, 13, the relative movement is circumferential and not axial as is the case with the ring seals of internal combustion engine pistons.

Variation of pitch angle of the blade is accommodated by rotation of the blade root 82 on the blade mounting stub 15 and this pitch variation is controlled and regulated by means of connections between the blade roots and a swash plate device mounted coaxially with the rotor mounting member 28. Each blade root 82 carries a lug 98 into which is screwed a hollow bolt 9| terminating in a pin 92 on which is mounted by means of a spherical bush 93 an eye [3| carried by one end of a link 94 (see Figs. 3 and 4) the other end of the link 94 is connected also by means of an eye I32 and a spherical bush (not shown) with an arm 95 rigidly secured to a ring 96 which-is rotatably mounted by means of a ball bearing 91 on a swash plate member 98 carried by means of a gimbal mounting 99,

I00 on a sleeve IOI embracing the rotor mounting.

member 28. The swash plate member 98 is provided with a lug I02 pivoted at I03 to the control column 34. Manipulation of the control column causes the swash plate to be tilted in any desired vertical plane. Y

The rotor blades are constrained against flapping relative to the hub, i. e. the path swept by the blade tips is maintained coaxial with the hub by means of a linkage. This mechanism consists of a central vertical extension I25 of the cover 10 on which is slidable a collar I26 which is connected to the blade roots 82 by links I21 having ball and socket joints I28 and I29 at each end. It will be clear that this linkage ensures that all the blades have the same coning angle relative to the hub.

The operation of the swash plate device is as follows:

If the common axis of the hub and the path some '7 swept bytheblade tips dcesnot coincide with the axis of the swash plate, the linkages Bil, 9%, 8'5 impose a cyclical variation of blade pitch angle". as the lug 9t lies'forward of the radial axis of the blade with reference to the direction of rotation, indicated by an arrow in Fig. 3, the phase of the cylical pitch variation will be such as to give rise to an aerodynamic couple acting on the rotor, tending to restore coaxiality or parallelism of the rotor and the swash plate, 1. e. to bring the axis of r-rotation of the hub in to .a position in which it coincides with or is parallel to theaxis ofthe swash plate. (Coincidence will only occur when the axis of the swash plate coincides with the centre line of the rotor mounting member 128.) The amplitude of the cyclical blade pitch variation induced by a relative inclination of the axes of the hub and the swash plate varies with the magnitude of this relative inclination and the ratio "between them depends upon the position of the eye i3l at the upper end of the link '94. Provision is made for adjusting this ratio by altering th position of the bolt 9| relative to the mg 90 with which it is in threaded engagement. In Fig. the bolt 9| is adjusted the position giving the minimum available'ratio of amplitude of blade pitch variation to inclination of hub axis to swash plate axis; although several threads of the bolt 9i are left projecting from the outboard end or the lug 90, further adjustment to reduce this projection would result in the links 94 ,fouling a part of the hub. In Fig. 51: a position of adjustment is shown giving a greater value of the abovementioned ratio, the head of the bolt Ell being right up to thelugllll and the lock-nut Wt being put on the other side of the lug. This does not represent the total range of adjustment, however, as .a further increase of the abovementioned ratio can be obtained by threading the bolt 9i into the lug Hi) the other way round, so that the pin 92 carrying the spherical bush .93 engaging the eye I131 ,is on the outboard side of the lug'QU and this further adjustment can be continued until onlyehough threads of the bolt iii are left projecting from the inboard end or" the lug' 9b to accommodate the lock-nut 13.0. The total range of values of the abovernentionedratio covered by the range of adjustment herein described is from 1/1 to 5/1 (but there is a short a are provided with threads of opposite hand .en-

gaging corresponding internal threads of 'the link 94. Lock-nuts I33, 134 are provided ,for locking the eyes 131, "IBZQ-after adjustment of the effective length of the link 94.. This latter adjustment is also used for initially egualising the pitch angles ,of theblades. It will also be seen that variation of ,coning angle of all the blades together induces an equal and simultaneous variation of the blade pitchangles through the action of thelin'kages-S'A et cetera which opcrate in such a way that .in'crease'oi coning angle brings about a decrease .of blade pitch angle and vice versa; this characteristic .conduces'lto stability in vertical gusts and provides automatic regulation of the rotor R..,'P. M. whenpower output is varied. It also ensures that ifflthe power is cut off the blade pitch angle assumes ,a value appropriate to auto-rotation. The ratio between variation of'coning angle and change of blade til) pitch angle can also be adjusted' byadjustm'g bolts ll but this ratio is not the same as that between the amplitude of cyclic blade pitch variation and inclination of the hub axis to the swash plate axis because coning of the blades takes place about the centre of the spherical joint 10 which is situated outboard from the centre of the rotor hub and its mounting member.

The tendency explained above of the axis of rotation of the rotor to remain coincident or parallel with the axis of the swash plate and to return'to such a position if disturbed, together with the interaction explained above of the coning angle and the mean blade pitch angle, ensure that the rotor is stable in all kinds of manoeuvres and in gusty air. Control of the attitude of the rotational axis of the rotor relative to the airframe is readily obtained by displacing the axis of the swash plate by means of the pilots controls as above described, the

rotational axis of the rotor being caused to lollowail displacements of the axis of the swash plate by means of the indirect control supplied by the linkage 94 et cetera.

The sleeve i'fli is slidable upon the rotor mounting member 28 and is provided with a lug Hi4 carrying a pin m5 engaging in a striking fork NW pivoted on a bracket Ill-I secured to the mounting member 28. The striking fork Hi5 ispivotall-y connected at )8 to the upright rod M, shown in 1. Movement of the pitch control lever '36 (see Fig. l) transmitted by the system of rods and levers 31, 38, 39, 4Q, 45, Bite the sleeve HM to shift the latter up or down on the mounting member 8. By this means the swash plate device is moved bodily up and down, and this displacement being transmitted by means of arms 95, links 94 and lugs to the blade roots "82, causes an equal and simultaneous variation of the pitch angle of all the blades.

The axes of the blade housings 14' are given aslight upward inclination corresponding to the normal coning angle of the blades, and are so positioned that with the blades in their normal coning angle the radial axes of the blades intersect one another at the centre of the spherical joint between the mounting member extension *41 and the packing rings 52, 53, i. e. the centre about which tilting of the tiltablemember-dfl, b9 which supports the hub takes place.

A rotor brake is provided comprising a brake drum Hi9 externally finned for air-coolingand secured .to the lower face of the hub 65 by studs Ho and internally expanding brake shoes 1H carried by a flanged plate H2 secured by st;uds 11.3 to the lower half '49 of the tiltable .member. The control mechanism of the brake shoes is not illustrated and maybe of any suitable known type. The splined shaft '51 and universal joint 58 which restrain the tiltable member from rotating on the rotor mounting member 18, '41

also serve to transmit the braking torque to the latter member.

The tube H4 thus provides a duct for the working fluid in continuation of the passage jormed between the parts 50 and El and the orifices 152, 64, I la.

Referring to Fig. 6,,it will be seen that the blade root 82 is reduced in cross section in an outboard direction and merges into a hollow spar H constituting the main structural member of the rotor blade 30. The secondary structure of the blade is indicated at H6 but will not be described in detail as it constitutes no part of this invention, but may be as disclosed and claimed in my copending application Serial No. 484,06 l filed coincidentally with the present case. The tube H 4 constituting the duct forthe working fluid is extended within the blade root 82 and terminates at H! at which point it fits tightly within the interior of the spar I I5, being secured thereto in any convenient manner. It will thus be seen that the tube H4 rotates with the blade 30 when the pitch angle varies and is therefore movable relative to the blade mounting stub 15. To prevent the tube H4 from binding on the blade mounting stub 15 a considerable clearance between these members is provided in order to allow for expansion eifects of the tube H4 which is exposed to the action of the hot gases flowing from the rotor mounting member into the blades. The spar H5 thus constitutes the duct for the working fluid within the blade itself, the outer part of which is illustrated in Figs. '7 to 9 in which it will be seen that the blade 30 terminates in a jet reaction nozzle device I I8, the internal conformation of which comprises an elbow duct H9 communicating with the hollow spar H5 and a convergent/divergent nozzle I20 terminating in a nozzle orifice l2l which is flush with the trailing edge of the blade and of elongated shape conforming to the blade profile. It will be seen from Fig. 8 that the whole nozzle device is of highly flattened form adaptedto fair into' the blade contour. The forward part of the nozzle device includes a weight I22 provided for mass balancing of the blade. This weight being placed well forward of the leading edge of the blade serves to bring the centre of gravity of the whole blade into a sufficiently forward position to prevent blade flutter in accordance with known principles.

In Figs. and .11 the outboard end of a, rotor blade having an alternative nozzle arrangement is shown. In this the nozzle element I23 constitutes a continuation of the ho low blade-soar I l 5 (shown in other figures) and the nozzle orifice I24 is of elongated narrow form being situated on the u per (low pressure) surface of the blade at about the region of maximum thickness. This arrangement is considered to have certain advantages as hereinbefore stated.

I claim:

1. In a helicopter, a bladed lifting rotor, at non-rotative mounting therefor, said rotor incorporating a tiltable a d rotatable hub and a plurality of sustaining blades mounted with freedom for fla ping movement about axes oifset from the hub axis whereby the plane of rotation of the blade tips may assume various inclinations with reference to the body of the aircraft and whereby the axis of rotation of the tiltable hub tends to remain coincident with the axisof-the cone generated by the radial axes of the blades in normal flight, the sustaining blades further being mounted for variation of pitch angle and the rotor incorporating mechanism for cyclically varying the bladepitch angle, said mechanism being automatically operative upon deviation of the blade tip path from a given plane to'vary the pitch in a sense tending to restore the blade tip path to said given plane, and in combination therewith rotor driving means including jetreaction devices mounted on or incorporated in the lifting blades of the rotor and means for supplying the jet reaction devices with a stream of I 10 reactive fluid, whereby no torque reaction is, transmitted from the rotor to its non-rotative mounting.

2. In a helicopter, an airframe, a hollow rotor mounting member rigidly mounted thereon, a tiltable member mounted on the mounting member by jointmeans allowing the former to tilt relatively to the latter in any vertical plane, but preventing relative rotation about a substantially vertical axis, a rotor comprising a hub freely rotatable on the tiltable member about a substantially vertical axis and a number of lifting rotor blades extending radially from the hub and articulated thereon for variation of blade pitch angle, a trunk for delivering fluid to the hollow mounting member, ducts within the mounting member and blades and registering orifices in the mounting member, tiltable member, hub and blades for delivering the fluid from the mounting member into the blades and jet reaction nozzles situated on the blades and communicating with said ducts for ejecting the fluid in a direction opposite to that of rotation of the rotor and thereby driving it without imposing torque reaction on the mounting member and airframe. I

3. In a helicopter as claimed in claim 2, mean for sealing the articular clearances between the mounting member, tiltable member, hub and blades against escape of the working fluid.

4. In a helicopter as claimed in claim 2, a rotor blade having a jet reaction nozzle device located thereon with its centre of gravity forward of the mass centre of the rest of the blade so that the mass of the nozzle device contributes to the mass balancing of the blade,.thereby assisting to prevent blade flutter.

5. In a helicopter as claimed in claim 2, a rotor blade incorporating a jet reaction nozzle situated substantially at the tip of the blade.

6. In a helicopter as claimed in claim 2, a rotor blade incorporating a jet reaction nozzle device,

.said device having a nozzle orifice situated at the trailing edge of the blade and lying flush therewith, the orifice being of radially elongated form and the whole nozzle device being faired into the blade contour.

7. In a helicopter as claimed in claim 2, a rotor blade incorporating a jet reaction nozzle device having a jet orifice situated on the upper face of the blade at about the region of maximum thickness the orifice being of radially elongated form.

8. In a helicopter as claimed in claim 2, means connecting the blades to the hub and constraining the path swept by the blade tips to be coaxial with the rotative axis of the hub.

9. In a helicopter as claimed in claim 2, means connecting the blades to the hub' permitting the blades to vary their coning angle with respect to the hub, but restraining them against flapping.

10. In a helicopter as claimed in claim 2, a swash plate device tiltable with respect to the mounting member in any vertical plane, pilots control means regulating the tilt of the swash plate device, and connections between the latter and the rotor blades for imposing and regulating v .plate device, and connections between the latter andthe rotor blades for imposing and regulatr ing cyclical variation of blade pitch angle, said '11 .connections embodying adjustable means for varying the ratio between the inclination oi?v the swash plate device relative to the axis of rotation of the hub and the amplitude ofv the ensuing cyclical variation of blade pitch.

1 2. In a helicopter as claimed in claim 2, means controllable by the pilot for varying the blade pitch angle of all the rotor blades equally and simultaneously;

13. In a helicopter as claimed in claim 2, joint means connecting the tiltable member to the rotor mounting member so constructed that the centre about which the former tilts is situated on the rotational axis of the rotor.

14. In a helicopter as claimed in claim 2, joint means connecting the tiltable member to the rotor mounting member so constructed, that the centre about which the former tilts is situated on the rotational axis of the rotor approximately at the vertex of the cone generated by the radial axes of the blades in normal flight.

15. In a helicopter as claimed in claim 2, means connecting the rotor blades to the hubpermitting a limited degree of leading and lagging of the blades from their mean radial positions independently of one another.

1 6. In a rotary wing aircraft, a sustaining rotor incorporating a tiltable and rotatable hub and a plurality of sustaining blades mounted with freedom for flapping movement about axes offset from the hub axis whereby the plane of rotation of the blade tips may assume various inclinations with reference to the body of the aircraft and whereby the axis of rotation of the tiltable hub tends to remain coincident with the axis of the cone generated by the radiai axes of the blades in normal flight, the sustaining blades further being mounted for variation of pitch angle and the rotor incorporating mechanism for cyclically varying the blade pitch angle, said mechanism being automatically operative upon deviation of the blade tip path from a given plane to vary the pitch in asense tending to restore the blade tip path to said given plane, and rotor driving means mounted on said blades and adapted to react between the blades and the atmosphere and constructed to impart a driving force to said rotor effective to sustain the aircraft without appreciable torque reaction between the rotor and the body of the aircraft.

17. In an aircraft, the arrangement of claim 16, with controllable means providing for tilting in all directions of the blade tip path relative to the aircraft.

18. In an aircraft, the arrangement of claim 16, with controllable means providing for tilting in all directions of the blade tip path relative to the aircraft, and in which the rotor hub is mounted for tilting about a center approximately coinciding with the center of intersection of the rotor axis of rotation and the longitudinal axes of the rotor blades.

19'. In a rotary wing aircraft, a non-tilting structure, a sustaining rotor comprising a rotatable member tiltable in all directions with respect to said structure, rotor blade means mounted for variable caning with. relation to said member and having means for variation of effective blade pitch, a rotor blade pitch controlling base member having a predeterminable position relative to sa1d non-tilting structure, and pitch control connections between said blade means and said. base member constructed to effect variation of blade pitch upon tilting of said first-mentioned member and upon movement of the blade means iii th coning sense, the center of tilt of said rotatable and tiltable member and the center of coning movement of the blade means being spaced apart, whereby the extent of. blade pitch change for a given;- angudar' range of coning is different from the extent of. blade pitch change for the same angular range of tilting of said member.

20. A construction according to claim 2 and further including blade pitch controlling -mechanism incorporating connections so coupled to the blade means as to cause cyclic blade pitch variation in a sense tending toward restoration of the hub to a predetermined equilibrium position upon angular displacement thereof from said position.

21. In a rotary wing aircraft, a non-tilting structure, a sustaining rotor comprising a rotatable member tiltable in all directions with respect to said structure, rotor blade means mounted for variable coning with relation to said membox and having means for variation of effective blade pitch, and mechanism for introducing and controllably regulating cyclic blade pitch variation, said mechanism further including a roto: blade pitch controlling base member movable to different positions with: relation to said nontilting structure, and further including pitch control connections between said blade means andv the said base member constructed to effect variation of blade pitch upontiltingof said first-mentioned member and upon movement or the blade means in the coning sense.

22. In a. helicopter employing jet reaction; drive, a rotor hub carrying blade mounting stubs on which rotor blades incorporating jet reaction nozzles are rotatably mounted for variation of blade pitch angles, means forconducting a reactive aascous fluid through: the hub and blade mounting stubs to theinterior of theblades and thence to the nozzles, and a gland between each blade mounting stub and its associated blade employing a spring ring sealing member in substantially gas-tight engagement therewith.

23. In a helicopter having a lifting rotor ineluding c hub, lifting blades incorporating jet reaction nozzles and means for conducting a reactive gaseous fluid from the hub through the blades to" the nozzles, blade mounting means including o hollow mounting stub supported on the hub, bearing means rotatably supporting a blade on the stub for blade pitch variation, and gas-sealing means operative between the stub and the blade comprising a part having an annulcr groove formed therein, a spring .ring loacted in the groove and a part having a cylindrical surface on which the spring ring bears,

24. In a helicopter employing jet reaction drive and having a fixed rotor mounting member, an intermediate member tz'ltablp but non-rotationally supported. thereon, a. rotor hub rotatab'ly supported on the tiltablemember, lifting rotor blades incorporating jet reaction nozzles mounted on the hub and means for conducting a reactive gaseous fluid. through the mounting member, 'tiltablc member, hub and blades to the jet nozales, combined bearing and gas-sealing means operative between the mounting member and the tiltab'l'e member including a ring of mouldedcarbon-base' material mounted in one of the two last-named members and having a spherically curved. face engaging a corresponding spherically curved face formed in the other of the two lastnamed members. 25.. A helicopter as claimedin claim 24, where the rptor movnti q member vm tiltable' member are. both provided with mutually registering peripheral outlet openings for the reactive fluid and wherein the bearing and gas-sealing means includes two moulded carbon rings located respectively above and below the peripheral openings, the spherically curved faces of the two rings having the same centre.

26. A helicopter as claimed in claim 24', wherein the rotor-mounting member and tiltable member are both provided with mutually registering peripheral outlet openings for the reactive fluid and wherein the bearing and gas-sealing means includes two moulded carbon rings located respectively above and below the peripheral openings, the spherically curved faces of the two rings having the same centre and radius.

27. A helicopter as claimed in claim 24, wherein the ring of carbon-base material is moulded into a recess formed in the tiltable member and en ages a spherical y curved face formed in the rotor-mounting member.

28. A helicopter as claimed in claim 24, wherein the spherically curved face of the ring. of

carbon-base material is a female face, the corresponding face of the cooperating member being male.

29. In a helicopter employing jet reaction drive and having a rotor hub and lifting rotor blades incorporating jet reaction nozzles, means being provided for conducting a reactive gaseous fluid from the hub through the blades to the nozzles, rotor blade mounting means comprising a blade mounting stub on which a blade is mounted and joint means connecting the stub to the hub comprising a ball member and a socket member,

together with combined centrifugal thrust bearing and gas-sealing means including an annular groove formed in the socket member and an insert of graphite-impregnated material moulded into the groove and engaging the surface of the ball member.

30. In a sustaining rotor for aircraft, a hub member having a passage for a gaseous medium, a rotor blade member having a passage for a gaseous medium, an interconnecting blade stub between said members, said blade stub having a blade pitch changing connection with one of said members and a blade swinging connection with the other of said members, through both of which connections the centrifugal load of the blade is carried, said stub further being so apertured as to interconnect said passages, and gas-sealing means between said stub and each of said members.

31. The construction of claim 30, in association with a non-rotative support having a passage communicating with the hub passage.

32. The construction of claim 30, in associawith a non-rotative support having a passage communicating with the hub passage, and combined bearing and gas-sealing means interposed between said support and said hub member.

33. In a sustaining rotor for aircraft, a fixed rotor support having an internal passage for a 'fluid medium, an intermediate member tiltably supported thereon, a rotor hub rotatably mounted on the tiltable intermediate member, and fluid passage means through said intermediate member and hub and communicating with said internal passage.

34. The construction of claim 33, in association with a rotor blade mounted on said hub and having a fluid passageway in communication therewith.

35. In a helicopter employing jet reaction drive and having a fixed rotor mounting member, an intermediate member tiltably supported thereon, a rotor hub rotatably supported on the tiltable intermediate member, lifting rotor blades incorporating jet reaction, nozzles mounted on the hub and means for conducting a reactive gaseous fluid through the mounting member, tiltable member, hub and blades to the jet nozzles.

36. The construction of claim 35, with combined bearing and gas-sealing means operatively interposed between the mounting member and tiltable member.

37. In a sustaining rotor for aircraft, a hub member and a blade member having intercommunicating fluid passageways, a centrifugal loadcarrying bearing between said members constructed to accommodate relative motion between the blade memberand the hub member, and a combined fluid seal and blade movement damper adjacent said bearing.

38. In a sustaining rotor for aircraft, a nonrotative support formed with an internal fluid passageway, a rotor hub with a blade rotating exteriorly of said support and having a fluid passageway in said blade adapted to communicate with the passageway first mentioned, and a tilting mounting for said hub on said support, comprising a spherical surface on the exterior of said support and combined spherical-bearing and fluid-sealing means operatively interposed between the hub and said support and adapted to accommodate hub tilting in all directions while preventing escape of the fluid medium.

39. In a helicopter employing jet reaction drive and having, a rotor hub and lifting rotor blades incorporating jet reaction nozzles, means bein provided for conducting a reactive gaseous fluid from the hub through the blades to the nozzles, rotor blade mounting means comprising a blade mounting stub on which a blade is mounted and joint means connecting the stub to the hub comprising a ball member and a socket member, together with combined centrifugal thrust bearing and gas-sealing means including an annular groove formed in the socket member and an insert of graphite-impregnated material moulded into the groove and engaging the surface of the ball member, and means for damping movements about the ball and socket joint means; said damping means including a ring of frictional material having a spherically curved face engaging the interior of the ball member, which is made spherically hollow and truncated for this purpose, a support immovably connected to the socket member, on which support the friction ring is axially slidable and spring means pressing the friction ring into engagement with the ball member.

40. In a sustaining rotor for aircraft, a hub member having a passage for a gaseous medium, a rotor blade member having a passage for a gaseous medium, an interconnecting blade stub between said members, said blade stub being apertured to provide for interconnection of said 7 passages and having a blade pitch changing connection with one of said members and a blade swinging connection with the other of said members, and gas-sealing means between said stub and each of said members together with a nonrotative support having an internal gas passage, an intermediate mounting member between said support and said hub member, rotor hub bearing means between said intermediate member and said hub member, and a tilting mounting between said support and said intermediate member, said 15 intermediate member having means of communication between the passage in said support and the passage through said hub member.

41. The construction of claim 40, with gassealin means between the non-rotatioe support and the intermediate mounting member.

42. The construction of claim 40, with gassealing means for the rotor-hub bearing means.

43. In a helicopter employing a'et reaction drive and having a fixed rotor mounting member, an intermediate member tiltablg supported thereon, a rotor hub rotatably supported on the tiltable intermediate member, lifting rotor blades incorporating jet reaction nozzles mounted on the hub, means for conducting a reactive gaseous fluid through the mounting member, tiltable member, hub and blades to the jet nozzles, and combined bearing and gas-sealing means operatioel'y interposed between the mounting member and tiltable member, including a ring mounted in one of the two last-named members and having a spherically curved face engaging a corresponding spherically curved face formed in the other of the two last-named members.

' CYRIL GEORGE PULLIN;

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